This invention relates to rotary cutting machines of the kind in which a large rotating drum which carries a series of knives cuts through a compressed material "cheese" (e.g. of tobacco) which is supported by a mouthpiece. The cutting knives are intermittently fed forward and continuously ground to maintain both a sharp knife edge and a consistent drum diameter because it is essential for good quality cutting that the cutting action takes place as close to the supporting mouthpiece as possible. The normal clearances between the knife tip and mouthpiece range from 0.006 inch - 0.015. inch
It follows from the above that any increase in the effective cutting radius above 0.005 inch will put the cutting knives on a collision course with the stationary mouthpiece resulting in damage, expensive repairs and loss of production.